Revealing the Superiority of Fast Ion Conductor in Composite Electrolyte for Dendrite-Free Lithium-Metal Batteries

Composite electrolytes composed of a nanoceramic and polymer have been widely studied because of their high ionic conductivity, good Li-ion transference number, and excellent machinability, whereas the intrinsic reason for the improvement of performance is ambiguous. Herein, we have designed a functional polymer skeleton with different types of nanofiller to reveal the superiority of fast ion conductors in composite electrolyte. Three types of ceramics with different dielectric constants and Li-ion transfer ability were selected to prepare composite electrolytes, the composition, structure, and electrochemical performances of which were systematically investigated. It was found that the addition of fast ion conductive ceramics could provide a high Li-ion transference ability and decreased diffusion barrier because the additional pathways existed in the ceramic, which are revealed by experiment and density functional theory calculations. Benefiting from the superiority of fast ion conductor, Li-metal batteries with this advanced composite electrolyte exhibit an impressive cycling stability and enable a dendrite-free Li surface after cycling. Our work enriches the understanding of the function of fast ion conductors in composite electrolyte and guides the design for other high-performance composite electrolytes in rechargeable solid batteries.

Automated summary

Composite electrolytes composed of nanoceramic and polymer are widely studied for their high ionic conductivity and good Li-ion transference number. This study investigates the addition of fast ion conductive ceramics in composite electrolytes, showing improved Li-ion transference ability and reduced diffusion barrier, leading to impressive cycling stability in Li-metal batteries. The research enriches understanding of fast ion conductors in composite electrolytes and provides guidance for designing high-performance composite electrolytes in rechargeable solid batteries.